Question 1

What is IGF-1 LR3?

Accepted Answer

IGF-1 LR3 (Long Arg3 IGF-1) is an analog of insulin-like growth factor 1 carrying two modifications: an arginine substitution at position three and a thirteen-amino-acid extension at the N-terminus. Together these substantially reduce affinity for IGF-binding proteins, so a larger free fraction remains available in culture media. That property is why the analog rather than the native protein is used as a reference standard in cell culture work and proliferation assays. Prime Science Supply supplies IGF-1 LR3 as a Research Use Only material, not intended for human or veterinary use.

Question 2

What does purity of at least 98% by HPLC-UV mean?

Accepted Answer

High-performance liquid chromatography with ultraviolet detection separates the components of a sample and measures the area under each resulting peak. A result of at least 98% purity means the peak corresponding to the target peptide accounts for at least 98% of the total detected area, indicating that truncated sequences, deletion products, and synthesis byproducts are present only in trace amounts. HPLC-UV is the standard characterization method for synthetic peptides in pharmaceutical and academic laboratories. 98% is the specification, which is a floor: the measured result for an individual lot is often higher. Where a Certificate of Analysis is issued for a lot, it reports the chromatographic result for that specific lot; CoA availability and level of detail vary by product and by lot.

Question 3

How should lyophilized peptides be stored?

Accepted Answer

Lyophilized peptide powder should be kept dry, sealed, and protected from light. Refrigeration at 2-8 °C is appropriate for short-term holding, while −20 °C or lower is used for extended storage of laboratory inventory. Moisture is the main variable to control, so a vial is best brought to ambient temperature before it is opened, preventing condensation from forming on the cold powder. Repeated freeze-thaw cycling should be avoided, since each cycle contributes to gradual degradation. Stability characteristics differ between sequences; consult the published literature for the specific peptide and any Certificate of Analysis issued for the lot.

IGF-1 LR3 (1 mg)

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